A gasoline direct injection (GDI) engine draws air into a plurality of cylinders and injects gasoline directly into combustion chambers of the cylinders using GDI fuel injectors. The air/fuel mixture is compressed by pistons and ignited by spark generated by spark plugs. The combustion of the compressed air/fuel mixture drives the pistons to generate torque at a crankshaft. Exhaust gas resulting from combustion is then expelled from the cylinders into an exhaust treatment system. The GDI fuel injectors are typically arranged in bored cavities in a cylinder head portion of the engine. A combustion seal is provided between each GDI injector and its respective combustion chamber. If these seals leak, some of the exhaust gas escapes from the combustion chamber past the combustion seal. The high temperature of the exhaust gas could potentially damage the GDI fuel injector, such as melting of molded plastic. Conventional techniques, such as knock monitoring, are unable to detect the combustion seal failure. Accordingly, while known fuel injection systems work well for their intended purpose, there remains a need for improvement in the relevant art.